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Can J Cardiol. 1997 Sep;13(9):811-5.

Anticoagulation in chronic nonvalvular atrial fibrillation: a critical appraisal and meta-analysis.

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  • 1British Columbia Office of Health Technology Assessment, University of British Columbia, Vancouver. cjgreen@unixg.ubc.ca

Abstract

OBJECTIVE:

To assess the outcomes associated with warfarin treatment of patients with chronic nonvalvular atrial fibrillation (CNVAF) for prevention of primary stroke.

DATA SOURCES:

MEDLINE was searched for literature published from 1987 to August 1996. Search terms used were 'atrial fibrillation' and 'anticoagulants'.

STUDY SELECTION:

Five published randomized controlled trials concerning primary stroke prevention.

DATA EXTRACTION:

Data were pooled across trials to estimate the magnitude of the effect for each of nine reported end-points. The annual probability of occurrence of each outcome was calculated, including standard errors and Mantel-Haenszel significance tests with 95% CIs.

DATA SYNTHESIS:

In view of the lack of blinded assessment and documented low inter-rater reliability of soft neurological end-points, the analysis was limited to the relatively objective end-points of major strokes, fatal strokes, major bleeding and fatal bleeding. Warfarin did not reduce the incidence of fatal strokes to a statistically significant extent, nor was incidence of fatal bleeding increased significantly. Warfarin reduced the absolute annual incidence of major strokes in patients with CNVAF by 0.89%, while at the same time it increased the absolute annual risk of major bleeding incidents by 1.8%. Though small, these differences were statistically significant.

CONCLUSIONS:

On balance, the margin between expected benefit and harm for warfarin prophylaxis in patients with CNVAF is uncomfortably thin. These results and conclusions differ from those of a previously published meta-analysis of these same studies.

Comment in

PMID:
9343029
[PubMed - indexed for MEDLINE]
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